Estate Living Magazine The Slow Movement - Issue 39 March 2019 | Page 46

L I v E
S M A R T
A COOLING SYSTEM THAT WORKS WITHOUT
ELECTRICITY
As we slither our sweltering way to the end of the hottest summer most of us can remember, we find
hope in an awesomely innovative technology developed by scientists at Stanford University in the
USA. Stanford scientists cooled water without electricity by sending excess heat where it won’t be
noticed – space. The specialised optical surfaces they developed are a major step toward applying this
technology to air conditioning and refrigeration.
It looks like a regular roof, but the top of the Packard Electrical Engineering Building at
Stanford University has been the setting of many milestones in the development of an
innovative cooling technology that could some day be part of our everyday lives. Since
2013, Shanhui Fan, professor of electrical engineering, and his students and research
associates have employed this roof as a test bed for a high-tech mirror-like optical surface
that could be the future of lower-energy air conditioning and refrigeration.
Research published in 2014 first showed the cooling capabilities of the optical surface on
its own. Now, Fan and former research associates Aaswath Raman and Eli Goldstein have
shown that a system involving these surfaces can cool flowing water to a temperature
below that of the surrounding air. The entire cooling process is done without electricity.
‘This research builds on our previous work with radiative sky cooling but takes it to the next
level. It provides for the first time a high-fidelity technology demonstration of how you can
Stanford researchers reflected in the
mirror-like optical surface they developed.
This photo from 2014 shows the reflectivity
of the mirror-like optical surface that
Fan, Raman and Goldstein have been
researching, which allows for daytime
radiative sky cooling by sending thermal
energy into the sky while also blocking
sunlight. The people in this photo (left to
right) are Linxiano Zhu, PhD ’16, co-author
of the 2014 paper, Fan and Raman. (Image
credit: Norbert von der Groeben)